#include <cstdio>
#include <cmath>

int main() {
    const int CLK_TCK = 100;
    long long C1, C2, C;
    int h, m, s;

    scanf("%lld%lld", &C1, &C2);
    C = (long long)round((C2 - C1) / 100.0);
    s = C % 60;
    m = C / 60 % 60;
    h = C / 60 / 60;

    printf("%02d:%02d:%02d\n", h, m, s);
}